1. Field of the Invention
The present invention relates to a bipolar battery, and in particular to an improved bipolar battery which is capable of increasing a current capacity by alternately stacking a plurality of anodes and cathodes in a cell for parallel connections.
2. Description of the Conventional Art
The current capacity of a battery is in proportion to the area of an electrode of the battery. For this reason, a wider area of the electrode is used for fabricating the battery having a large current capacity. Since there is a limitation for increasing the area of the electrode, a battery having a desired current capacity has been fabricated by connecting a plurality of electrodes with a predetermined area in parallel. Then, in order to obtain a predetermined voltage of the battery, the cells with parallel connections in such a manner are connected in series. However, this type of monopolar battery requires a cell case capable of preventing a flow of electrolyte between the cells in order to minimize a current loss due to the flow of the electrolyte between the cells, i.e., inter-cell leakage current. Besides, cell terminals are necessary for implementing a serial connection of the cells, thereby complicating the battery connections and increasing the size of the batteries. In order to overcome the above-described problems, a bipolar batter can be employed, which is capable of obtaining a desired voltage capacity by simply stacking a cell, composed of a cathode, a separator, and an anode on top of a current collector without an additional cell case.
However, in order to increase the current capacity of the bipolar battery, the area of the same should be increased. The conventional bipolar battery will be explained with reference to the accompanying drawings.
FIG. 1 illustrates a structure in which conventional bipolar cells are stacked. As shown therein, a cell is composed of an anode 1 and cathode 3 isolated by a separator 2, an outer ring 4 supporting the cathode 3, the separator 2 and the anode 1, an electrolyte injection hole 5 through which an electrolyte is injected into the cathode 3 and the anode 1, and a current collector 6 stacked underneath the cathode 3. A plurality of the above-described cells are stacked in a manner that the anode 1 of a lower cell and the cathode 3 of an upper cell share a collector 6.
In the bipolar battery, the additional cell case for preventing the flow of the electrolyte between the cells and external wiring for serial connections are not necessary, thereby resulting in a simpler battery design. A bipolar battery with a desired voltage can be fabricated based on the number of the stacked cells.
However, in the conventional bipolar battery, the area of each electrode should be increased for high current capacity. Therefore there is a limitation to fabricate a battery having a larger current capacity.